Britain’s regional cities are highly vulnerable to Paris-style terror attacks because they lack the 24/7 armed police cover given to London, the home secretary has been warned by police chiefs co-ordinating counter-terrorism.

Officers at Scotland Yard have briefed Theresa May that “dedicated armed assets” outside the capital are sparse. An exercise carried out by the National Counter-Terrorism Command aimed at examining how the UK’s police would respond to a simultaneous attack on London, Birmingham and a smaller provincial city has further highlighted the perils. A Scotland Yard source said: “Ask a regional force how long it would take them to respond to a terror attack and watch them squirm.”

The revelation comes in the wake of reports that the mastermind of the Paris terror attacks, Abdelhamid Abaaoud, visited the UK on a false passport. It was reported he may have been in Kent before meeting fellow extremists in London. It was earlier reported that he had photographs of Birmingham landmarks on his phone and that he had called numbers belonging to Moroccans there.

Seven terror plots in the UK have been foiled in the past six months alone; the current threat level is “severe”. Shadow home secretary Andy Burnham said: “It is essential that all our major cities have 24/7 protection from attack. If this is true, it suggests there are worrying gaps in our ability to respond.”

A Home Office spokesperson said that in recent weeks an extra £34m has been provided to fund more armed police. And it is understood that counter- terrorism chiefs are negotiating with May over a plan to assemble four dedicated regional armed units to be available seven days a week, and late into the night. It has also been proposed that “stand-by” teams, ringfenced from other operational duties, be made available to the regions on 15 minutes’ notice.

Critics believe the Home Office is determined to further run down parts of the security apparatus to meet budget cuts. Last week it emerged through a leaked document that a third of emergency vehicles kitted out to deal with a “dirty bomb” or other major contamination incidents in England were to be axed. The memo, circulated to all fire services two weeks ago, revealed that 22 of 65 vehicles – carrying decontamination showers, tents and one-piece suits – will be made redundant.

That cut comes on top of a 15% drop in armed officers since 2008, from nearly 7,000 to 5,875. Forces to have seen falls include Greater Manchester, down 27%, Merseyside, 25%, and West Midlands, 12%. The largest reduction is in Warwickshire, which saw a 47% cut. And only a few firearms officers are counter-terrorist specialists trained to deal with sieges and hostage situations.

Following January’s attack on the Charlie Hebdo offices in Paris, deputy chief constable Simon Chesterman, of the National Police Chiefs’ Council, hinted at the current risks. He wrote in Top Cover, the journal of the Police Firearms Officers’ Association: “The prospect of a nationwide manhunt for armed terrorists who have gone to ground after an attack is deeply concerning. Could the UK respond to incidents like the ones in Paris? I believe we have the capability: capacity is a different issue.”